Abstract

Endothelin-1 (ET-1) has proinflammatory properties and contributes to allergic late-phase responses. As basophils play a key role in allergic rhinitis or asthma, we investigated the effect of ET-1 on basophils.

Cells were isolated from venous blood of healthy donors via magnetic cell sorting. To show ETA or ETB receptor expression RT-PCR was performed. The chemotactic effect of ET-1 [10-6-10-16M] was analysed in modified Boyden chambers (positive control MCP-1 [10-8M]). To explore ET-1 signalling, cells were preincubated with BQ-123 [10-6-10-16M] or BQ-788 [10-6-10-16M]. Migration depth was quantified microscopically. Histamine release upon ET-1 [10-6-10-12M] and upon additional stimulation with the secretagogue fMLP [10-5M] was determined by ELISA.

The RT-PCR revealed basophils to express both, ETAR and ETBR. ET-1 [10-6-10-8M] further proved to be a strong chemoattractant for human basophils (p<0.0001). Despite basophils express both receptors, only the ETAR antagonist BQ-123 [10-6-10-12M] significantly blocked migration towards ET-1 [10-8M]. Furthermore, the histamine release was increased by 2.46 to 2.6 fold after ET-1 stimulation [10-6-10-12M]. Interestingly, only the evoking of histamine release by additional stimulation with fMLP [10-5M] resulted in a dose dependent effect of ET-1, showing ET-1 [10-8M] to be most effective.

Our observations reveal for the first time that basophils express ETAR and ETBR and ET-1 induces histamine release and basophil migration, which seems ETAR dependent. Considering the fact that ET-1 is involved in the mechanisms of airway inflammation, targeting ET-1 by receptor antagonists may be a new option in the treatment of allergic airway disease.